Consultant psychiatrist and lead researcher Dr Lisa Page, Sussex Partnership NHS Foundation Trust said: ‘Our study found that people with serious mental illness are at increased risk of death during hot weather. Therefore mental health service users should take action to protect themselves during hot weather, for example getting themselves to a cool place, wearing cool clothing and taking enough fluids.’
The findings, published in the June issue of the British Journal of Psychiatry add to the growing evidence that people with mental illness are a vulnerable group during hot weather, and have implications for public health strategies during heat waves.
Senior researcher Professor Louise Howard, King’s College London Institute of Psychiatry adds: ‘People who are most at risk from the heat often do not appreciate that they are – we are hoping our research will raise awareness about this vulnerability during heat waves, particularly regarding inpatient mental health services which need to ensure adequate environments.’
The study used the General Practice Research Database to identify people with a diagnosis of psychosis, dementia, alcohol misuse and drug misuse who had died in England over a 10-year period from 1998-2007. In total, there were 22,562 deaths –a mean of 6.18 deaths each day. Daily temperature data across the same period for all monitoring stations in England were downloaded from the British Atmospheric Data Centre.
The researchers found that patients with mental illness faced an increased risk of death of about 5% per 1oC increase in temperature above 18oC. This is greater than the risk for the general population, which has an increased risk of around 3% per 1oC increase in temperature.
The increased risk of death was more marked among younger patients, those living in southern and eastern parts of England, those who had been diagnosed with drug or alcohol problems, and those who were taking antipsychotics.
The researchers believe there are several biological and social factors that may increase mortality among people with mental illness during hot weather. People with mental illness are more likely to be socially isolated or living in institutional care – both of which are risk factors for heat-related death. Antipsychotic medication can also affect people’s ability to regulate their body temperature by reducing sweating.
People with substance misuse problems may be vulnerable during hot weather because alcohol depresses the central nervous system causing dehydration, and opiates can affect the body’s physiological response to heat.
Given that the elderly are often associated with high death rates during heat waves, the researchers were surprised to find that patient under 65 were at greater risk of death than older patients. However, they believe this may be because the majority of older people in the study had dementia, and may have received better care during periods of hot weather than younger people with alcohol or drug misuse problems.
Dr Page said: ‘We found a marked increase in risk of death for people with psychosis, dementia and substance misuse during hot weather, and suggests that people with mental illness may be a vulnerable group. Some public health strategies, such as the English ‘Heatwave Plan’ already identify patients with mental health problems as being a high risk group. But more attention may need to be paid to patients with alcohol and drug misuse problems, who are often not under the care of mental health services.’
Professor Howard concluded: ‘Given that global temperatures will continue to rise and the frequency of heat waves is predicted to increase in the years to come, these findings suggest that the consequences of climate change may be felt disproportionately by the mentally ill.’
The study was funded by the UK Medical Research Council and the BUPA Foundation.
For full paper: Page, L.A. et al. ‘Temperature-related deaths in people with psychosis, dementia and substance misuse’ British Journal of Psychiatry (June 2012) doi: 10.1192/bjp.bp.111.100404
For more information, please contact Seil Collins, Press Officer, Institute of Psychiatry, email: firstname.lastname@example.org or tel: 0207 848 5377